Evaluation of Corrosion Inhibition of Essential Oil-Based Inhibitors on Aluminum Alloys.

There is a high demand for eco-friendly, effective, and high-performance corrosion inhibitors for industrial applications. Thus, the corrosion property of aluminum alloys was studied in essential oil-containing sodium chloride solution at various concentrations. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), surface tests, and weight loss analysis were used to study the corrosion inhibition mechanism of the essential oil. The essential oil showed the highest inhibition efficiency of 97.01% at 1000 ppm. A high efficiency of 96.03% was achieved even after 168 h of exposure. The potentiodynamic polarization test showed that the essential oil is a mixed-type inhibitor. EIS results show better adsorption of the oil on the surface of the aluminum at increased inhibitor concentrations. The Langmuir's adsorption isotherm model was found to describe the adsorption behavior. The surface morphology of the uninhibited and inhibited specimens examined by a scanning electron microscope equipped with an energy-dispersive X-ray spectroscope confirmed the protective film of the inhibitor molecules on the aluminum surface.